desc:Simplooper
// Copyright 2026 James Teh
// License: GNU General Public License version 2.0

// Set a slider to 1 to trigger its action. This is ideal for triggering from a
// MIDI button or pedal which sends 127 when pressed and 0 when released.
slider1:0<0,1,1>Track1 Record
slider2:0<0,1,1>Track1 Play/Stop
slider3:0<0,1,1>Track2 Record
slider4:0<0,1,1>Track2 Play/Stop
slider5:0<0,1,1>Track3 Record
slider6:0<0,1,1>Track3 Play/Stop
slider7:0<0,1,1>Track4 Record
slider8:0<0,1,1>Track4 Play/Stop
slider9:0<0,1,1>Reset

@init

MAX_SAMPLES = 48000 * 20; // 20 seconds
NUM_TRACKS = 4;

STOPPED = 0;
PLAYING = 1;
RECORDING = 2;

prevResetSlider = 0;

memPos = 0;
function allocateArray(size) local(origMemPos) (
	origMemPos = memPos;
	memPos += size;
	origMemPos;
);

trackState = allocateArray(NUM_TRACKS);
prevRecSlider = allocateArray(NUM_TRACKS);
prevPlaySlider = allocateArray(NUM_TRACKS);
bufL = allocateArray(NUM_TRACKS);
bufR = allocateArray(NUM_TRACKS);

t = 0;
loop(NUM_TRACKS,
	bufL[t] = allocateArray(MAX_SAMPLES);
	bufR[t] = allocateArray(MAX_SAMPLES);
	prevRecSlider[t] = 0;
	prevPlaySlider[t] = 0;
	t += 1;
);

function reset() (
	t = 0;
	loop(NUM_TRACKS,
		memset(bufL[t],0,MAX_SAMPLES);
		memset(bufR[t],0,MAX_SAMPLES);
		trackState[t] = STOPPED;
		t += 1;
	);
	loopLen = 0;
	setLoopLen = 0;
	loopPos = 0;
);

reset();

@slider

// Reset
slider9 == 1 && prevResetSlider != 1 ? (
	reset();
);
prevResetSlider = slider9;

t = 0;
loop(NUM_TRACKS,
	// Record trigger
	recSlider = slider(t * 2 + 1);
	recSlider == 1 && prevRecSlider[t] != 1 ? (
		trackState[t] == RECORDING && loopLen == 0 ? setLoopLen = 1;
		trackState[t] = RECORDING;
	);
	prevRecSlider[t] = recSlider;

	// Play toggle
	playSlider = slider(t * 2 + 2);
	playSlider == 1 && prevPlaySlider[t] != 1 ? (
		trackState[t] == RECORDING && loopLen == 0 ? setLoopLen = 1;
		trackState[t] = (trackState[t] == PLAYING ? STOPPED : PLAYING);
	);
	prevPlaySlider[t] = playSlider;

	t += 1;
);

@sample

// Detect first loop length
loopLen == 0 && loopPos > 0  && (setLoopLen || loopPos == MAX_SAMPLES) ? (
	loopLen = loopPos;
	loopPos = 0;
);

// Playback
isActive = 0;
outL = 0;
outR = 0;
t = 0;
loop(NUM_TRACKS,
	trackState[t] != STOPPED ? (
		isActive = 1;
		outL += bufL[t][loopPos];
		outR += bufR[t][loopPos];
	);
	t += 1;
);

// Record
inL = spl0;
inR = spl1;
t = 0;
loop(NUM_TRACKS,
	trackState[t] == RECORDING ? (
		bufL[t][loopPos] += inL;
		bufR[t][loopPos] += inR;
	);
	t += 1;
);

// Advance loop position
isActive ? (
	loopPos += 1;
	loopLen > 0 && loopPos >= loopLen ? loopPos = 0;
);

// Just output from the loop buffer. Don't pass input through.
spl0 = outL;
spl1 = outR;